The present invention relates to a roofing material and more particularly to a roofing underlayment including anti-slip properties.
In both residential and commercial roofing applications, a roof covering material is utilized to provide the main water protection barrier. Whether the primary roof covering material comprises composition shingles, metal panels or shingles, concrete or clay tiles, wood shakes, or slate, a primary roof covering material is used to protect the building interior from water ingress.
Roofing underlayment is sometimes described as Type I and Type II roofing underlayments as specified in Chapter 15 of the IBC (International Building Code), and defined in Chapter 9 of the IRC (International Residential Code); and is also specified as Type 15 and Type 30 underlayments in Chapter 15 of the UBC (Uniform Building Code). The present invention will find utility as potential substitutes for these underlayment types, or simply as a useful underlayment in various roofing construction projects.
In some circumstances, whether due to primary roofing material design, installation practices, or accidental breach of the primary roofing material, water can penetrate the primary roofing material. To protect the building interior in these circumstances, it is common to provide a secondary layer called a roofing underlayment, beneath the primary layer. The roofing underlayment acts as a water and moisture barrier.
A variety of roofing underlayment products is commonly used. The two major classes are mechanically attached and self-adhered underlayments, the latter commonly referred to as “peel and stick”.
It is desirable that a roofing underlayment provide a surface which has a sufficiently high coefficient of friction (“COF”) to increase the safety for an applicator to walk upon. The coefficient of friction describes the ratio of the force of friction between two bodies and the force pressing them together. The coefficient of friction is an experimentally determined value. The phrase “high coefficient of friction” in this document means a sliding coefficient of friction of at least 0.5 when tested with dry leather and at least 0.7 when tested with dry rubber (per CAN/CGSB-75.1-M88).
Underlayments should be easily affixable to a roofing surface, for example by nailing or adhesion. They should ideally be impermeable to moisture. High tensile and tear strengths are also desirable to reduce tearing during application and exposure to high winds. Underlayments should be light in weight to facilitate ease of transport and application, and should be able to withstand prolonged exposure to sunlight, air and water.
A common mechanically attached roofing underlayment product used in the United States and Europe is bituminous asphalt-based felt, commonly referred to as “felt.” Typically, this felt comprises paper felt saturated with asphaltic resins to produce a continuous sheeting material which is processed into short rolls for application.
Such felts generally demonstrate good resistance to water ingress and good walkability in dry and wet roof conditions. Disadvantages include very low tensile and tear strengths, relatively high weight per unit surface area, a propensity to dry and crack over time, very low resistance to ultraviolet (“UV”) exposure, high likelihood of wind blow off, and a propensity to absorb water causing buckling and wrinkling, thus preventing the application of direct primary roofing materials such as composition shingles.
To overcome these shortcomings, several products have been marketed with high tensile and tear strengths. These materials are generally reinforced non-woven polymeric synthetic materials, rather than asphaltic felts. They are generally lightweight, thin, have higher tensile, tear and burst strengths as compared to felts, and are superior to felts in UV resistance and resistance to drying and cracking over time.
A major drawback of these polymer underlayments is their low COF on the walking surface in dry or wet conditions. This problem limits the commercial attractiveness of such products in high pitch roofs or in climates characterized by frequent and sporadic wet or humid conditions. Thus, a roofing underlayment made from a polymer material which also provides anti-skid properties would be ideal for use in a roofing membrane.